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PT0225(11/05)

Ver: 0

3

Data Sheet

PT7C4302

Real-time Clock Module (3-wire Interface)

Pin Configuration

X1

X2

GND

VCC1

SCLK

I/O

6

7

8

1

2

3

VCC2

4

5

RST

PT7C4302

DIP-8

SOIC-8

Pin Description

Pin no.

Pin

Type

Description

1

VCC2

P

Primary power. When VCC2 is greater than VCC1 + 0.2V, VCC2 will power the PT7C4302.

2

X1

I

Oscillator Circuit Input. Together with X2, 32.768kHz crystal is connected between them.

3

X2

O

Oscillator Circuit Output. Together with X1, 32.768kHz crystal is connected between them.

4

GND

P

Ground.

5

RST

I

Reset. The reset signal must be asserted high during a read or a write. This pin has a 40kΩ

internal pull-down resistor.

6

I/O

I/O

Serial Data Input/Output. I/O is the input/output pin for the 3-wire serial interface. The pin

has a 40k

Ω internal pull-down resistor.

7

SCLK

I

Serial Clock Input. SCLK is used to synchronize data movement on the 3-wire serial

interface. The pin has a 40k

Ω internal pull-down resistor.

8

VCC1

P

Backup power. When VCC2 is less than VCC1, VCC1 will power the PT7C4302. VCC1

provides low-power operation in single supply and battery-operated systems as well as low

power battery backup. In systems using the trickle charger, the rechargeable energy source is

connected to this pin. UL recognized to ensure against reverse charging current when used in

conjunction with a lithium battery.